Field of the Invention
The invention relates to a testing device having a test gas container and a test leak.
Description of Related Art
For testing the tightness of hollow bodies to be tested, such as food packages, for example, leak testing systems are used that subject the hollow body under test to a defined differential pressure or to a defined pressure for a predetermined period of time. The variation of the external pressure over this period of time serves as an indication of an existing leak in the hollow body. The leak testing systems have to be checked for functionality at regular intervals. For this purpose, testing devices are used that simulate the leaky hollow body by comprising a test gas container provided with a test leak for producing a test gas flow at a predefined leakage rate. In this regard, the test leak is formed by at least one capillary tube connecting the interior of the test gas container with the outer environment thereof in a gas-conducting manner.
The test gas container serves as a source of the test gas supplied to the leak testing device via the test leak. Conventional test gas containers are typically of a rigid design, being made of metal, for instance. Test gas containers with permeation leaks or with capillary leaks exist that each have a defined leakage rate. The leakage rate is defined by the leakage rate of the capillary tube or the membrane and by the differential pressure between the test gas container and the environment.
For leak test systems that test the tightness of packages, for example, testing devices are required that are used regularly at recurring intervals and provide test leaks with a relatively high leakage rate. With rigid test gas containers, there is a difficulty that a high leakage rate causes a great pressure drop within the test gas container and the test gas container often has to be refilled in order to avoid that the leakage rate drops too quickly. The volume of the known test gas containers is comparatively small, since the testing device must not be much larger than the objects to be tested. For this reason, it is not possible to increase the volume of the test gas container as desired, so as to decrease the pressure drop in the test gas container.
It is an object of the invention to provide an improved testing device for producing a test gas flow with a predefined leakage rate.
The testing device of the present invention is defined by the features of claim 1.